bye the chance i am iranian consequently i have commuincated with cornuopia of people and students who have been studying english.however,it seems difficult they have surpassed the obstacles and they are shining in english in spite the fact that sadtosay our country is concealed under political shadows and there is not any special cmmunication for our people to another foriegn people.therefore i can exemplify my people as one of smartest nations in the world.in hope of having more global communication and advocation.

Again, purely anecodotally, I've particularly enjoyed working with Korean students. From my experience they're ideal students. They're hard working, conscientious and also seem willing to speak and don't seem too afraid to make mistakes.

Of course, these qualities can be found anywhere and as you point out we must be careful not to generalise (although generalising can be fun and helps us deal with the world) but when I saw this question I immediately thought of Koreans.

... and further to this idea of generalising, I can't remember where this quote comes from - and I might be paraphrasing - but I think it's fantastic: "Your prejudices are the windows through which you views the world; just take care to clean them once in a while."